const arrayTest = [

    {name: 'Silver', experience: 10},

    {name: 'Kevin', experience: 5},

    {name: 'Happy', experience: 1},

    {name: 'Xan', experience: 1}

]

let sum = 0;

function total(experience) {

    return sum += experience

}

arrayTest.forEach(el => total(el.experience))

console.log(sum)